CODEWITHSUNDEEP
arp
Selva
Selva

Reputation: 19

ARP : What Mac ARP does request when a Host want to communicate to Host in different Network

Please Clarify my doubt in ARP. In the below Topology,. Looking for better understanding, how ARP works when Hosts are connected between default Gateways .

Host A(10.10.10.1)-----Switch-----(10.10.10.2)Router(20.20.20.2)--------HostB

  1. When a Host want to communicate to Host B , does hostA send an ARP request for Destination IP (20.20.20.1) or to Default Gateway (10.10.10.2) .
  2. If it send ARP for HOST B mean, Host A identifies Host B is in different network, it will send the Packet only to the Configured Default Gateway , so will it request for Default Gateway Mac address
  3. Host B mac will not be learnt by Host A by any cost, So does Host A will generate ARP request for each time?

Upvotes: 0

Views: 150

Answers (1)

Ron Maupin
Ron Maupin

Reputation: 6452

Since a MAC address is only useful for a layer-2 domain which is bounded by a layer-3 device (router), a host will not ARP for a MAC address on a different subnet unless it has a misconfigured mask.

The host will ARP for the address of its configured gateway so that it can send the frame to the gateway, and the gateway will remove the layer-2 frame and try to forward the layer-3 packet to the port toward the end host. The router will then encapsulate the layer-3 packet with a new layer-2 frame (possibly using ARP if the nest hop isn't in its ARP cache) for the next link.

Upvotes: 1

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